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4 Signs Your AC May Need a Refrigerant (Freon) Charge

2020 Jun 22
Posted in: Air Conditioning

Refrigerant is the “blood” of your AC system. Without the right amount, your system won’t be able to cool your home properly. But, determining whether or not your AC system needs refrigerant can be tricky because low refrigerant “symptoms” can also be the symptoms of other AC issues (we’ll dig into that later).

However, if you think your AC may be low on refrigerant, look for these 4 signs:

  • Your energy bills have increased
  • You notice warm air coming from your vents
  • There’s ice or frost forming on your AC
  • Your AC is making a hissing or bubbling noise

In this blog, we'll explain the 4 "signs" above and how low refrigerant might be the culprit. We'll also explore other reasons you may be noticing each sign so that you can determine whether you actually have a refrigerant issue or not.

Prefer to speak with a professional? We get it! We’ve had lots of experience working with refrigerant issues, so no matter what is going on, we will be able to diagnose the problem and find a solution. Learn more about the AC repair services we offer or schedule service!  

Sign #1: Increased energy bills

If you notice that your energy bills have increased and you haven’t made significant changes to your home’s temperature, you may have a refrigerant leak.

As we mentioned above, refrigerant is the “blood” of your AC system. Your AC blows warm air over an evaporator coil which is full of refrigerant. The refrigerant then picks up that heat from the air and carries that heat outside where it’s dumped. 


If there is not enough refrigerant in your AC system, your AC can’t get rid of as much heat per cooling cycling, meaning your system will need to run longer and work harder to cool your home. Longer run times mean higher energy bills

Other issues that can cause increased energy bills

While increased energy bills are a sign of low refrigerant, increased energy bills can also be the result of:

  • An aging AC system- If your AC system is 10+ years old, your high energy bills are likely the result of an aging system.  Over time, your AC becomes less efficient, which means it has to work longer and results in increased energy bills.
  • A system that’s too small or too large for your home-  If your AC system was recently installed, your high energy bills could simply be caused by a system that is too small or too large for your home. A system that is too small will have to work constantly to meet demand and a system that is too large will constantly turn on and off. Both of these scenarios use more energy than if your system was to just run steadily, which can increase your cooling bills.
  • A dirty air filter- If your AC system is neither new nor 10+ years old, our next suggestion would be to check your AC filter. If it’s dirty, it could be restricting airflow to your AC system, which will make your AC work longer. 

If you have a clean filter, your system is properly sized and is under 10 years of age, you probably have a refrigerant leak. 

Sign #2: Warm air blowing from supply vents 

As we mentioned above, refrigerant absorbs heat from your home’s air and transfers it outside. If refrigerant levels are low, your AC can't absorb enough heat per cycle, meaning you may notice warmer air blowing from your supply vents.

Other issues that can cause warm air to blow from vents

Before you call a professional to come and recharge your system, we’d recommend replacing your air filter. If your AC filter is clogged, it can prevent your system from pulling in enough warm air (meaning there will be less cool air for your AC to blow out).

Clean air filter (left) next to a dirty air filter (right)

However, if you have replaced your AC filter and you notice that your AC system is still producing warm air, you probably do have low refrigerant levels and should reach out to a pro.

Sign #3: Ice or frost on your AC

If you spot ice or frost anywhere on your AC, it could be a sign that your refrigerant levels are low. When refrigerant levels get too low, it can cause the temperature of the refrigerant to drop below normal design temperatures. Eventually, this will cause ice to build on the refrigerant lines and the evaporator coil.

Other issues that can cause ice/frost to build

  • Dirty air filter- Low airflow can cause your evaporator coil to freeze, and if your air filter is clogged, it could reduce the airflow to your AC system. So, if you haven’t checked your air filter already, you should do that before calling a professional. 
  • Closed vents- As we mentioned above, low airflow can cause your evaporator coil to freeze. To prevent this, you should ensure that all of your vents are open and unobstructed.

If you’ve checked your air filter and ensured that your vents are all open, you likely have a refrigerant leak and will need to reach out to a professional for help. 

Sign #4: Hissing or bubbling noise 

If you hear a hissing or bubbling noise coming from around your outdoor AC unit, chances are it’s the sound of refrigerant escaping through a leak.

If you hear hissing, that means the refrigerant is escaping in gas form. If you hear bubbling, it’s leaking via liquid form.

Other issues that cause a hissing/bubbling noise

Not many other AC issues cause a hissing or bubbling noise, so if you hear this sound, you likely have a refrigerant leak. You’ll want to call a professional ASAP to come and repair it.

Getting your air conditioner fixed

If you suspect you have a refrigerant leak, you’ll need to contact a professional to check it out. Refrigerant is a toxic substance, so it’s not something you can legally fix on your own.

But a word of warning: Refrigerant isn’t “used up” like gas in a car. If you are low on refrigerant, you have a leak in your AC system. So, if a tech simply tops off your refrigerant without fixing the leak, it is a temporary solution and you will likely be in the same situation again soon.

Make sure they find the leak, evacuate the remaining refrigerant, repair the leak and then add the appropriate amount of refrigerant for your system. 

Live in the Phoenix area and need an air conditioning contractor to fix your refrigerant issues? Contact George Brazil.